From Book 1:
Geronimo isn't the only world-famous adventuring journalist from New Mouse City; introducing his fabulous sister, Thea!
The Thea Sisters are five fun, lively students at Ratford College on Whale Island, who want to be real, live journalists just like their hero, Thea Stilton. Between classes and friendships, love and small fits of jealousy, they're finding college life is really exciting! In "The Secret of Whale Island," it's the start of the new school year and the students have arrived at Ratford College. Every year at this time, the whales move off the coast of Whale Island, but this time, a savage killer whale threatens the peace.